G4eSingleCoulombScatteringModel.cc

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//  G4eSingleCoulombScatteringModel.cc
// -------------------------------------------------------------------
//
// GEANT4 Class header file
//
// File name:    G4eSingleCoulombScatteringModel
//
// Author:      Cristina Consolandi
//
// Creation date: 20.10.2012  
//                           
//  Class Description:
//  Single Scattering model for electron-nuclei interaction.
//  Suitable for high energy electrons and low scattering angles.
//
//
// Reference:
//      M.J. Boschini et al. "Non Ionizing Energy Loss induced by Electrons 
//      in the Space Environment" Proc. of the 13th International Conference 
//      on Particle Physics and Advanced Technology 
//
//  (13th ICPPAT, Como 3-7/10/2011), World Scientific (Singapore).
//  Available at: http://arxiv.org/abs/1111.4042v4
//
//
// -------------------------------------------------------------------
//
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#include "G4eSingleCoulombScatteringModel.hh"
#include "G4SystemOfUnits.hh"
#include "Randomize.hh"
#include "G4ParticleChangeForGamma.hh"
#include "G4Proton.hh"
#include "G4ProductionCutsTable.hh"
#include "G4NucleiProperties.hh"
#include "G4NistManager.hh"
#include "G4ParticleTable.hh"
#include "G4IonTable.hh"

#include "G4UnitsTable.hh"


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using namespace std;

G4eSingleCoulombScatteringModel::G4eSingleCoulombScatteringModel(const G4String& nam)
  : G4VEmModel(nam),

    cosThetaMin(1.0),
    isInitialised(false)
{
    fNistManager = G4NistManager::Instance();
    theIonTable = G4ParticleTable::GetParticleTable()->GetIonTable();
    fParticleChange = 0;

    pCuts=0;
    currentMaterial = 0;
    currentElement  = 0;
        currentCouple = 0;

        lowEnergyLimit  = 0*eV;
    recoilThreshold = 0.*eV;
    particle = 0;
    mass=0;
    currentMaterialIndex = -1;

    Mottcross = new G4ScreeningMottCrossSection(); 

}

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G4eSingleCoulombScatteringModel::~G4eSingleCoulombScatteringModel()
{ delete  Mottcross;}

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void G4eSingleCoulombScatteringModel::Initialise(const G4ParticleDefinition* p,
                                           const G4DataVector&  )
{
    SetupParticle(p);
    currentCouple = 0;
    currentMaterialIndex = -1;
    cosThetaMin = cos(PolarAngleLimit());
    Mottcross->Initialise(p,cosThetaMin);
 
        pCuts = G4ProductionCutsTable::GetProductionCutsTable()->GetEnergyCutsVector(3);


    if(!isInitialised) {
      isInitialised = true;
      fParticleChange = GetParticleChangeForGamma();
    }
}

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G4double G4eSingleCoulombScatteringModel::ComputeCrossSectionPerAtom(
                                const G4ParticleDefinition* p,
                G4double kinEnergy, 
                G4double Z, 
                G4double , 
                G4double, 
                G4double )
{

    SetupParticle(p);
 
    G4double cross =0.0;
    if(kinEnergy < lowEnergyLimit) return cross;

    DefineMaterial(CurrentCouple());

    //Total Cross section
        Mottcross->SetupKinematic(kinEnergy, Z);
    cross = Mottcross->NuclearCrossSection();

    //cout<< "....cross "<<G4BestUnit(cross,"Surface") << " cm2 "<< cross/cm2 <<endl;
  return cross;
}

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void G4eSingleCoulombScatteringModel::SampleSecondaries(
                   std::vector<G4DynamicParticle*>* fvect,
                   const G4MaterialCutsCouple* couple,
                   const G4DynamicParticle* dp,
                   G4double cutEnergy, 
                   G4double)
{
    G4double kinEnergy = dp->GetKineticEnergy();
    //cout<<"--- kinEnergy "<<kinEnergy<<endl;

    if(kinEnergy < lowEnergyLimit) return;
    
    DefineMaterial(couple);
    SetupParticle(dp->GetDefinition());

    // Choose nucleus
    //last two :cutEnergy= min e kinEnergy=max
    currentElement = SelectRandomAtom(couple,particle,
                      kinEnergy,cutEnergy,kinEnergy);

    G4double Z  = currentElement->GetZ();
    G4int iz    = G4int(Z);
    G4int ia = SelectIsotopeNumber(currentElement);

    //cout<<"Element "<<currentElement->GetName()<<endl;;   

    G4double cross= Mottcross->GetTotalCross();

    if(cross == 0.0) { return; }
            
    G4ThreeVector dir = dp->GetMomentumDirection(); //old direction
    G4ThreeVector newDirection=Mottcross->GetNewDirection();//new direction
    newDirection.rotateUz(dir);   
  
    fParticleChange->ProposeMomentumDirection(newDirection);   
  
    //Recoil energy
    G4double trec= Mottcross->GetTrec();

  //Energy after scattering 
  if(trec > kinEnergy) { trec = kinEnergy; }
  G4double finalT = kinEnergy - trec;
  G4double edep = 0.0;

  G4double tcut = recoilThreshold;
  if(pCuts) { 
    tcut= std::min(tcut,(*pCuts)[currentMaterialIndex]); 
  }

  if(trec > tcut) {

    //cout<<"Trec "<<trec/eV<<endl;
    G4ParticleDefinition* ion = theIonTable->GetIon(iz, ia, 0);

    //incident before scattering
    G4double ptot=sqrt(Mottcross->GetMom2Lab());
    //incident after scattering
    G4double plab = sqrt(finalT*(finalT + 2.0*mass));
    G4ThreeVector p2 = (ptot*dir - plab*newDirection).unit();
    //secondary particle
    G4DynamicParticle* newdp  = new G4DynamicParticle(ion, p2, trec);
    fvect->push_back(newdp);
  } else if(trec > 0.0) {
    edep = trec;
    fParticleChange->ProposeNonIonizingEnergyDeposit(trec);
  }

  // finelize primary energy and energy balance
  if(finalT <= lowEnergyLimit) { 
    edep += finalT;  
    finalT = 0.0;
  } 
  fParticleChange->SetProposedKineticEnergy(finalT);
  fParticleChange->ProposeLocalEnergyDeposit(edep);

}

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